D.A.(Tony)Stewart
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I doubt there will be any perfect systems using central proximity and low power as a requirement.
The perimeter fence only detects crossing or approaching the fence from either side.
The central transponder method suffers from large path loss variations due to interfering "objects" or should that be "subjects"?
In any case there needs to be direct line of sight for most methods unless you go with XHF like X-Ray frequencies.
-ultrasonic has good reflections off walls. NG
-infrared has Rx orientation issues.. NG
-microwave has path loss issues NG
-optical has path loss issues.
- mobile pulsed beacon with multiple receivers might mitigate some path loss issues.
A central broadband pulsed carrier or multi-band carrier to mobile Rx can mitigate path loss issues but cost more.
So your conceptual requirement seems not very practical unless you refine it with more conditions and relaxed tolerances, in other words a better spec.
The perimeter fence only detects crossing or approaching the fence from either side.
The central transponder method suffers from large path loss variations due to interfering "objects" or should that be "subjects"?
In any case there needs to be direct line of sight for most methods unless you go with XHF like X-Ray frequencies.
-ultrasonic has good reflections off walls. NG
-infrared has Rx orientation issues.. NG
-microwave has path loss issues NG
-optical has path loss issues.
- mobile pulsed beacon with multiple receivers might mitigate some path loss issues.
A central broadband pulsed carrier or multi-band carrier to mobile Rx can mitigate path loss issues but cost more.
So your conceptual requirement seems not very practical unless you refine it with more conditions and relaxed tolerances, in other words a better spec.
